Sleep is more than just a time for your body and mind to rest. In fact, while you're asleep, your body is hard at work.

During this time, your body rebuilds muscles you've worn down during the day and cleans away harmful plaques and waste that are produced in the brain. These are vital processes that keep both your mind and body running properly ().

Your mind also processes and responds to important emotions and experiences from the day and commits them to memory ().

Sleep is also essential to regulating your emotions. In fact, being sleep deprived for just one night can increase your emotional response to negative feelings by 60% ().

Not to mention, a lack of it makes it difficult for your body to regulate essential things like appetite control, your immune system, good metabolic function and your ability to maintain a normal body weight (, ).

Lastly, sleep plays an important role in regulating your circadian rhythm, or internal clock.

This inner clock runs on an approximately 24-hour schedule and regulates when you feel awake and sleepy. It may also help regulate things like metabolism, immune function and inflammation (, ).

Not sleeping long enough, sleeping at odd times of the day and exposure to bright light at night may throw off this inner clock and the many processes it regulates ().

While you may think you're getting ample rest, not all sleep is created equal. Not only is it important to get enough each night, but it's also important to get good-quality sleep.

Nevertheless, there's no universal definition for sleep quality.

However, it may be defined as how long it takes you to fall asleep, how often you wake up during the night, how rested you feel the next day or how much time you spend in different stages of sleep ().

Because good sleep is necessary to so many aspects of good health, you should make getting enough each night a high priority.

Summary: Getting enough quality sleep is necessary for various reasons, including maintaining your immune system and metabolic function, processing the day's memories and maintaining a normal body weight.

One study found that getting only five hours per night for several nights in a row decreases mental performance to the same extent as drinking enough alcohol to have a blood alcohol content of 0.06 ().

As if that wasn't enough, poor sleep can make you feel more negative, less productive and act less ethically at work (, ).

Every individual has unique needs and preferences, and the answer to how much sleep you need is no different.

Nevertheless, the amount of sleep you need per night is largely determined by your age.

Official recommendations for sleep duration are broken down by age group ():

Older adults (65+): 7–8 hours

Adults (18–64 years): 7–9 hours

Teenagers (14–17 years): 8–10 hours

School children (6–13 years): 9–11 hours

Preschoolers (3–5 years): 10–13 hours

Toddlers (1–2 years): 11–14 hours

Infants (4–11 months): 12–15 hours

Newborns (0–3 months): 14–17 hours

However, some people might need more or less sleep than is generally recommended, depending on the following factors.

Genetic Makeup

Genetics is another determinant of how many hours of sleep you need per night.

Certain genetic mutations can affect how long you need to sleep, at what time of day you prefer to sleep and how you respond to sleep deprivation ().

For example, those with one specific genetic mutation get by fine on around six hours, whereas people without it really need about eight hours, on average ().

And people carrying certain other genetic mutations are more negatively affected by sleep deprivation or experience deeper sleep ().

Unfortunately, your genetic makeup is not something you can change, and there's no practical way to know if you carry one of these mutations.

Therefore, it's important to simply pay attention to how you feel to determine if you're getting the right amount of sleep.

Sleep Quality

The quality of your sleep can also impact how much you need.

If your sleep quality is poor, you may find that you still feel tired after getting what should be considered enough.

Conversely, if you are getting good quality sleep, you may be able to manage better with a little less.

Many studies have found that short sleep duration, as well as poor sleep quality, are responsible for many negative sleep-related effects (, , , ).

Therefore, it's not only important to focus on sleeping long enough, but also on sleeping well enough.

Additionally, many common sleep disorders can have negative effects on your sleep quality, such as . If you regularly feel like you aren't sleeping well or are extremely tired and don't know why, it's a good idea to check in with your doctor.

Summary: How much sleep you need depends on many different factors, including your age, genetics and how well you sleep at night. Nevertheless, 7–9 hours per night is ideal for most adults.

Follow a regular schedule: Going to bed at the same time each night helps regulate your inner clock. Following an irregular sleep schedule has been linked to poor sleep quality and duration (, ).

Create a calming bedtime routine: Adopting a relaxing routine before bed can help you get in the mood to sleep. For example, listening to calming music has been shown to help improve sleep quality in certain groups ().

Create a comfortable environment: Sleeping in a quiet, dark room at a comfortable temperature can help you sleep better. Being too active before bed, too warm or in a noisy environment is linked to poor sleep (, ).

Minimize caffeine, alcohol and nicotine: Studies have linked caffeine, alcohol and nicotine use to poorer sleep quality. Try to avoid caffeine in the afternoon and evening (, , , ).

Reduce your use of electronics: The excessive use of cell phones and electronics has been associated with poor sleep quality. Even exposure to bright room lights before bed may negatively affect your sleep (, ).

Be more active: Studies have shown that being inactive is associated with poorer sleep, and conversely, getting exercise during the day may help you sleep better at night (, , , ).